Self and g



@with tutta stwt ffir.

HARRY S. BARTHOLOMEW, CF BRISTOL, CONNECTICUT, ASSIGNOR TO HIM- SELF ANDG. W. BARTHCLCMEW, OF THE SAME PLACE.

Letters Patent No. 65,046, dated M'ag/ 2S, 1867.

IMPROVEMENT IN- BRAGES I-OR BORING-BITS.

TO `ALL WHOM IT MAY CONCERN:

Be it known that I, HARRY S. BARTHOLOMEW, of Bristol, county ofHartford, and State of Connecticut, have invented certain lnew anduseful improvements in Bit-Stocks; and to enable others skilled inthe'art to make and use the same, I will proceed to describe, byreferring to the drawings, in which the same letter indicate like partsin .each of the figures. l

The nature of this invention will be understoodfrom the specificationand drawings. It relates to the mode of construction of that portion ofa bit-stock in which the bit is held true and firmly in its properposition withoutl having bestowed any special pains in fitting the bitthereto. In the accompanying drawings- Figure 1 is a bitfstock fashionedafter this improvement.

Figure 2 is a section view of the same broken oil` from the brace.

Figure 3 is an outside view of the bit-holder having itsfastening-sleeve removed therefrom, showing the edge'of one of the jaws,and the dove-tail by which said jaws are held in place andv renderedself-adjustable, and the position and location of the spring by whichsaid jaws are actuated, and the screwthread upon which the sleeve isarranged, so that by turning said sleeve thereon the jaws will becompressed or relaxed equally distant from the centre ofthe' diameter ofthe holder or hitopening.

In iig. 3 .Av is the end of a bit-stock in which the bit is secured foruse, having a. slit, c, c ut through -the centre thereof, in which thejaws are arranged to fit closely and work freely. Nea-r the lower endand across the face surface of this slit c are formed protuberanees a,the oiceof which is to hold the jaws in their proper places. l3 areholding-jaws, in the lower or back endof which are formed depressions a.Thus a dove-tail is formed upon the end of the jaws. C is an ellipticspring, or its equivalent, arranged in the base of the slitc, so thatwhen the depression a is placed on to the protuberance a and the jaw-Bin the slit c, said dove-tail formation will rest upon and he actuatedby the spring C to keep the outer ends of said jaws diverging from eachother. The inside face of these jaws is provided with angulardepressions D, commencing just back of the front end and terminating ata point on the surface near the back end. el are the griping-jaws orclamps formed in the outer end of the jaws B. The outside surface ofthese jaws is curved or concave shape, the object of which is to form awedge, b, near the front end of the jaws, so thatl by turning saidsleeve forward on to or over saidwedge b, it (the sleeve) will compressthe jaws firmly upon any tool placed between them. -E is a screw-threadformed on the body of the stock just hack of the slit c. F is a sleevewhich is fitted closely and woks' freely upon said stock. This sleeve isprovided with a screw-thread or depression to allow it to receive, orworkupon,'the screw-thread E.

Now, it will be readily seen thatJJy inserting the shank of a hit intothe depressionD through the opening in the end of the stock, (in theusual way,) until the small end of the shank fills the divergingdepression D, then, by turning the sleeve firmly 'on to or over thewedge or curved-shape jaws, they (the clamps d in the end of said jaws)will gripe the square, round, or spindle portion of the bit close to itsshank. Thus tools or bits of various sizes will be held true and firm,without the necessity of fitting the same thereto, as in the usual way.IbelieveI have thus shown the nature, construction, and advantage ofthis invention, so as to enable others skilled to make and use the sametherefrom.

I claim the protuherance a upon the socket A, with a correspondingdepression, a', in the jaws, suhstautially as and for the purposedescribed. i

' HARRY S. ABARTHOLOMEW. [L 5.]

Witnesses:

Trios. G. KNIGHT, JEREMY W. Buss.

